INFEWS: N/P/H20: From Antinutrients to Water Pollutants: Exploring the Behavior of Polyphosphate Anions in Aqueous Solutions

植酸盐是一种常见的分子，存在于玉米和其他植物材料的外壳中。它在食物中的存在会干扰包括猪和鸡在内的许多动物消化道对营养物质的吸附。结果，动物饲料中的蛋白质和重要的金属离子变得不可用，造成这些动物制成的肉制品效率的巨大损失。在美国国家科学基金会化学部大分子、超分子和纳米化学项目的支持下，宾夕法尼亚州立大学的Paul S. Cremer教授正在研究植酸盐和类似的阴离子（带额外负电荷的分子），以了解它们与金属离子的相互作用，并了解这些高负电荷的物质是如何导致蛋白质和其他大分子从水溶液中沉淀的。这项工作不仅有助于阐明如何更有效地利用牲畜饲料，而且有助于培养化学科学专业的研究生和本科生。这些研究的简化版本正被用作更新课程和实验室的跳板，这些课程和实验室用于教授高中学生分子间力和非共价相互作用。克里默小组正在探索植酸盐和二价金属阳离子在水溶液中的相互作用。各种阳离子与单个磷酸基团之间的相互作用通常是相似的，但当金属离子与多个磷酸基团同时相互作用时，这种情况发生显著变化，其中离子可以桥接相邻的磷酸基团。离子结合的热力学与聚阴离子水合壳的信息相关联，这些信息可以通过拉曼光谱和振动和频率谱获得。这些研究还被扩展到了解离子结合和水合水结构如何影响水溶液中蛋白质和多肽的盐化，作为pH值、盐浓度和特定阳离子身份的函数。除了在肌醇环周围含有6个磷酸基团的植酸盐外，正在进行的研究还包括在肌醇环周围放置1到5个具有特定立体化学性质的磷酸基团。测量也被用于平面膜形式的磷脂酰肌醇脂，以阐明与表面结合的多磷酸基团和在散装溶液中的多磷酸基团结合行为的差异。

Phytate is a common molecule found in the husks of corn, as well as other plant materials. Its presence in food can interfere with the adsorption of nutrients in the digestive track of many animals, including pigs and chickens. As a result, proteins and vital metal ions present in the animals' feed are rendered unavailable, causing an enormous loss in efficiency in the meat products made from these animals. With the support from the Macromolecular, Supramolecular and Nanochemistry Program of the NSF Chemistry Division, Prof. Paul S. Cremer at the Pennsylvania State University is studying phytate and similar anions (molecules with extra negative charge) to understand their interactions with metal ions and to learn how these highly negatively charged species cause the precipitation of proteins and other large molecules from water solutions. This work not only helps shed light on how livestock feed can be used more efficiently, but also helps train graduate and undergraduate students in the chemical sciences. Simplified versions of these studies are being used as a springboard to update the curriculum and laboratories used to teach high school students about intermolecular forces and non-covalent interactions. The Cremer group is exploring interactions between phytate and divalent metal cations in aqueous solutions. The interactions between various cations and individual phosphate groups are often similar, but this changes markedly when metal ions interact simultaneously with multiple phosphate groups, where the ions can bridge adjacent phosphate moieties. The thermodynamics of ion binding is being correlated with information on the polyanion's hydration shell that can be obtained by Raman and vibrational sum frequency spectroscopy. Such studies are also being extended to understand how ion binding and hydration water structures affect the salting out of proteins and polypeptides from aqueous solutions as a function of pH, salt concentration, and specific cation identity. In addition to phytate, which contains six phosphate groups around an inositol ring, studies are being performed with one through five phosphate groups placed around the ring with specific stereochemistry. Measurements are also being made with phosphatidylinositol lipids in planar membrane formats to elucidate the difference in binding behavior of polyphosphate groups bound to surfaces and those in bulk solution.